Reactivation of TET2 reverses vascular smooth muscle cell osteogenic differentiation and prevents medial aortic calcification

Cardiovascular diseases often manifest with vascular calcification. Vascular calcification is an active process orchestrated by contractile vascular smooth muscle cell (VSMC) phenotypic switch to an osteoblast-like cell. Here, we identified that the DNA demethylase, Tet2 (Ten-eleven translation 2), safeguards VSMCs from transitioning into the osteogenic lineage and loss of Tet2 promotes development and progression of vascular calcification. Tet2 was among the most significantly downregulated epigenetic markers in calcified aortas. VSMC-specific loss of Tet2 promoted VSMC osteogenic differentiation and enhanced vascular calcification as evidenced histologically, molecularly, and hemodynamically. In vivo studies further indicated that Tet2 inhibits calcification-associated VSMC apoptosis and medial thinning. Notably, calcified regions were enriched in a Trem2hi (triggered receptor expressed on myeloid cells 2) macrophage subpopulation. Intervention studies using high-dose ascorbate to enhance Tet2 enzymatic activity resulted in significantly reduced medial aortic calcification and improved aortic structural integrity in mice. Ascorbate treatment in human aorta organ cultures was sufficient to reduce calcification development in diseased tissues, and restore contractile properties to the calcified aorta. This study highlights the potential clinical impact of modulating Tet2 activity in managing cardiovascular disorders associated with vascular calcification.